{
  description = "Chirp!";

  inputs = {
    zig.url = "github:mitchellh/zig-overlay";
  };

  outputs = {
    self,
    zig,
    pkgs,
  }: let
    nixosModule = {
      config,
      lib,
      pkgs,
      ...
    }: {
      options.services.chirp = {
        enable = lib.mkEnableOption "Chirp";

        port = lib.mkOption {
          type = lib.types.port;
          default = 8080;
          description = "Port to listen on";
        };
      };

      config = lib.mkIf config.services.chirp.enable {
        systemd.services.chirp = {
          description = "Chirp SystemD Service!";
          wantedBy = ["multi-user.target"];
          after = ["network.target"];
          serviceConfig = {
            ExecStart = "${zig.packages.master}";
            Restart = "always";
            Type = "simple";
            DynamicUser = "yes";
          };
          environment = {
            PORT = toString config.services.chirp.port;
          };
        };
      };
    };
    in {
      # TODO: packages.default build
      apps.default = {
        type = "app";
        program = "${zig.packages.${pkgs.system}."0.14.0"} build run";
      };
    }
    // {
      nixosModules.default = nixosModule;
    };
}